KR20090034234A - Transceiver of which the reveiver and transmitter share the filter - Google Patents

Abstract

An RFID transceiver in which a transmitting unit and a receiving unit share a filter is provided to enable the transmitting unit and the receiving unit share predetermined configuration elements in an RF/analog terminal of the RFID transceiver, thereby reducing the entire circuit area. An RFID(Radio Frequency Identification) transceiver comprises a filter(104), a transmitting mixer(106) and a controller(110). The filter selectively receives a receiving base band signal or a transmitting base band signal. And the filter filters the signals. The transmitting mixer performs frequency up-converting of the transmission base band signal which is filtered. And the transmitting mixer produces a transmission wireless frequency signal. The controller controls input signal selection of the transmitting mixer and the filter.

Description

RFC transceiver where the transceiver shares a filter {TRANSCEIVER OF WHICH THE REVEIVER AND TRANSMITTER SHARE THE FILTER}

The present invention relates to a radio frequency identification (RFID) transceiver. More specifically, it relates to radio frequency and analog circuit stages of RFID.

Currently, ubiquitous network technology is receiving a lot of attention, and ubiquitous network technology refers to a technology that enables natural access to various networks regardless of time and place. Such ubiquitous network technology can be implemented in various ways by using communication technologies such as telematics communication, short-range wireless communication, and mobile communication, and RFID technology is emerging as one of ubiquitous network technologies.

RFID refers to a technology for automatically recognizing data stored in a tag, label, card, etc. in which a microchip is embedded in a reader using radio frequency. The RFID system attaches tags to objects to be managed, such as goods, and recognizes identification information and surrounding environment information using radio waves to collect, store, process, and track the information of each object to locate, remotely process, and manage the objects. And various services such as information exchange between objects. RFID has a merit of being able to recognize a plurality of tags at the same time in a non-contact manner, having a short recognition time, storing a large amount of data in the tags, and allowing semi-permanent use. Therefore, RFID is expected to be a next-generation core technology that will complement the shortcomings of existing barcodes and magnetic recognition devices and improve the convenience of use.

RFID system is composed of tags, readers, servers (middleware and application service platform), and is used in conjunction with wired and wireless communication networks. The tag is located on the object with information that can recognize the object, and the reader has a communication function for collecting and processing the information of the object and transmitting the information to the server. The server uses the information of the object to perform application processing.

The RFID reader transmits power and commands capable of operating the passive tag to the tag as a radio carrier signal, and receives a response from the tag to restore the signal. The RFID reader system is composed of an RF / analog unit and a digital signal processing control unit. The RF / analog unit includes a transmitter for transmitting power and data to a tag and a receiver for receiving data from the tag. The digital signal processing controller includes a decoder, an encoder, a clock generation circuit, a memory, a processor, and a host interface.

In order to activate the RFID, it is required to reduce the unit cost of the tag and the reader, and to reduce the unit cost of the reader, a circuit design that can simplify or maintain the performance of the analog unit of the transceiver while maintaining or improving performance is required.

In order to solve this problem, an RFID transceiver according to an embodiment of the present invention includes a filter for selectively receiving and filtering a reception baseband signal or a transmission baseband signal, and a signal for which the transmission baseband signal is filtered by the filter. A transmission mixer for generating a transmission radio frequency signal by up-converting a frequency, and a control unit controlling input signal selection of the transmission mixer and the filter.

Here, preferably, the RFID transceiver according to the embodiment of the present invention generates a received baseband signal by frequency downconverting a signal amplified by a low noise amplifier (low noise amplifier) for amplifying a received radio frequency signal, a low noise amplifier And a drive amplifier for amplifying the receive mixer and the transmit radio frequency signal.

Here, preferably, the RFID transceiver according to an embodiment of the present invention is a digital-analog converter for converting a transmission digital signal into a transmission baseband signal, and a signal in which the reception baseband signal is filtered by a filter. It further comprises an analog-to-digital converter for converting to a received digital signal.

Here, preferably, the RFID transceiver according to the embodiment of the present invention further comprises a first switch for selecting a signal input to the filter, the first switch is controlled by the controller.

Here, preferably, the transmission mixer selectively receives a signal filtered by a filter or a predetermined continuous wave signal, and the RFID transceiver according to an embodiment of the present invention comprises a second switch for selecting a signal input to the transmission mixer. Further, the second switch is controlled by the control unit.

Here, preferably, the RFID transceiver according to an embodiment of the present invention further includes a third switch for selectively transmitting the output signal of the filter to an analog-to-digital converter or a transmission mixer, wherein the third switch is controlled by the controller. do.

Here, preferably, the RFID transceiver according to the embodiment of the present invention further includes a low noise buffer in front of the filter for low noise amplifying the received baseband signal.

Here, preferably, the RFID transceiver according to an embodiment of the present invention further includes a programmable gain amplifier for amplifying the signal filtered by the filter.

Here, preferably, the filter is a lowpass filter or a bandpass filter.

In the RF / analog stage of the RFID transceiver, the transmitter and receiver share a predetermined component, thereby reducing the overall circuit area of the transceiver. In addition, it is possible to reduce the power consumption by the bias of the shared components, thereby achieving the overall power consumption savings.

Hereinafter, an RFID transceiver according to the present invention will be described in detail with reference to the accompanying drawings. Those skilled in the art will be able to clearly understand and easily implement the spirit of the present invention from the following detailed description. Like elements throughout the drawings are represented by like reference numerals.

1 is a block diagram of an RFID transceiver according to an embodiment of the present invention. Referring to FIG. 1, an RFID transceiver according to an embodiment of the present invention receives a signal transmitted from a tag and extracts digital information, and converts the input digital information into an analog signal, and then converts the digital information into an RF signal. It includes a transmitter. The receiver includes a low noise amplifier (Rx LNA) 101, a receive mixer (Rx Mixer) 102, a lowpass filter (LPF) 104, and an analog-digital converter (ADC) 108 And a transmitter comprises a digital-analog converter (DAC) 109, a low band filter 104, a transmit mixer Tx Mixer 106, and a drive amplifier TxDA 107. Include. Here, the low band filter 104 is shared by the receiver and the transmitter. In addition, the RFID transceiver according to an embodiment of the present invention includes a control unit 110 to share the low-band filter 104 in the receiver and the transmitter.

Here, a bandpass filter may be used instead of the low band filter 104 as necessary. For the sake of simplicity, the present specification mainly describes the case where the low band filter 104 is adopted, but the band pass filter instead of the low band filter 104 is used within the scope of the present invention. It should be construed as being included in the scope. Hereinafter, the functions and connection relationships of the respective components will be described in detail.

First, the case where the RFID transceiver receives a signal from a tag will be described. 1 is a diagram illustrating a signal transmission path when an RFID transceiver receives a signal from a tag. The radio frequency signal RxRF received through the antenna is low noise amplified by the low noise amplifier 101. Since the tag does not usually include an independent power supply and transmits the signal again using the power of the signal received from the RFID transceiver, the power level of the signal received from the tag is very low and the signal-to-noise ratio is very low. Therefore, the low noise amplifier 101 serves to amplify only a signal while suppressing amplification of noise as much as possible.

Thereafter, the signal amplified by the low noise amplifier 101 is frequency downconverted in the reception mixer 102 to generate a reception baseband signal RxBS. The receive mixer 102 generates a signal of baseband frequency by multiplying a radio frequency (RF) signal amplified by the low noise amplifier 101 with a signal of a constant frequency generated by a local oscillator (not shown). A phase locked look may be included to keep the frequency generated by the local oscillator constant. When the signal-to-power ratio of the baseband signal output from the mixer 102 is low, a low noise buffer (not shown) may be selectively provided to amplify the baseband signal while suppressing amplification of noise.

Thereafter, the output signal of the receive mixer 102 is passed to the low band filter 104 to pass only the frequency components of the region of interest below a certain frequency and block other frequency components. Here, a band pass filter may be used instead of the low band filter 104 as necessary. The bandpass filter passes only frequency components within a specific band and blocks other frequency components. If the amplitude of the filtered signal is less than required, a programmable gain amplifier (not shown) may be provided after the low band filter 104 to amplify the signal filtered by the low band filter 104. Herein, the gain of the programmable gain amplifier may be arbitrarily adjusted according to the magnitude of the received signal, or the gain may be adjusted to a value predetermined by the user.

The analog-to-digital converter 108 then converts the analog signal amplified by the low pass filter 104 into a received digital signal RxDS.

In the transmitting end, a continuous wave of a single tone having a predetermined baseband frequency is frequency upconverted in the transmission mixer 106 while the receiving end converts a signal transmitted from a tag into a digital signal. Amplified by the drive amplifier 107 and transmitted to the tag. The signal sent to the tag thus serves to supply the power necessary for the tag to transmit the signal. In order to generate a continuous waveform having a predetermined baseband frequency, the transmitting end of the RFID transceiver according to an embodiment of the present invention may include a continuous waveform generator (CW generator) (111). Here, as an example of the continuous waveform generator, a variable DC generator may be used. Alternatively, instead of the continuous waveform generator 111, a continuous waveform may be generated by appropriately converting a frequency of a signal generated from the local oscillator.

Next, a case where the RFID transceiver transmits a signal to a tag will be described. 2 is a diagram illustrating a signal transmission path when an RFID transceiver transmits a signal to a tag. The transmission digital signal TxDS to be transmitted is input to the digital-analog converter 109. Digital-to-analog converter 109 converts the input digital information into a baseband analog signal. Thereafter, the baseband analog signal to be transmitted is passed only by a band below a certain frequency by the lowband filter 104 and the remaining components are cut off. In this case, the low band filter 104 should have an appropriate bandwidth depending on when the transceiver transmits and receives the signal. Accordingly, the low band filter 104 is preferably a variable bandwidth low band filter capable of adjusting the bandwidth. The bandwidth of the low band filter 104 may be controlled by the controller 110 to be described later. The filtered signal is then sent to the transmit mixer 106.

The transmit mixer 106 multiplies the transmit baseband signal TxBS by a signal of a predetermined frequency generated by a local oscillator (not shown) to generate a radio frequency signal TxRF by up-converting the frequency. Thereafter, the drive amplifier 107 amplifies and transmits a radio frequency signal.

As described above, the low band filter 104 performs signal processing both when the RFID transceiver transmits a signal and when it receives the signal. That is, the transmitting end and the receiving end share the low band filter 104. For this sharing, the RFID transmitter according to an embodiment of the present invention includes a control unit 110. The controller 110 controls the input signal selection of the transmission mixer 106 and the low band filter 104. When receiving a signal from a tag, the transmit mixer 106 receives a signal from the continuous wave generator 111 and the low band filter 104 receives a signal from the receive mixer 102. When transmitting a signal with a tag, the transmit mixer 106 receives a signal from the low band filter 104 and the low band filter 104 receives a signal from the digital-to-analog converter 109. The control unit 110 controls the selection of the signal input to the transmission mixer 106 and the low band filter 104 according to whether to transmit or receive the signal in this way. Referring to FIGS. 1 and 2, the controller 110 is shown to be included in the RF / analog terminal of the RFID transceiver. This is to help understanding of the present invention, and the controller 110 may be physically included in the RF / analog terminal. It is not necessary to perform the role of the controller 110 by using an RFID baseband modem, a micro controller unit (MCU), or a similar control device. In this case, the RFID baseband modem, The micro control unit or other control device is the control unit 110 as meant herein.

For such control, the RFID transceiver according to an embodiment of the present invention may include, for example, a first switch (SW2) 103 and a second switch (SW1) 105. The first switch 103 selects a path from which the signal is input to the low band filter 104 between the reception mixer 102 and the digital-to-analog converter 109. The selection of the signal path is controlled by the controller 110. In addition, the second switch 105 selects a path from which the signal is input to the transmission mixer 106 among the continuous wave generator 111 and the low band filter 104. The selection of the signal path is controlled by the controller 110.

In addition, the RFID transceiver according to an embodiment of the present invention may include a third switch 112 for selecting the path of the output signal of the low-band filter 104. When the RFID transceiver receives a signal, the output of the low band filter 104 is sent to the analog-to-digital converter 108, and when transmitting the signal, the output of the low band filter 104 is the second switch 105. Via transmit to transmit mixer 106. The selection operation of the third switch 112 is controlled by the controller 110.

Next, with reference to Figure 3 will be described in detail the operation of the control unit 110 of the RFID transceiver according to an embodiment of the present invention. 3 is a diagram illustrating a timing diagram of a control signal of the control unit 110 and whether or not a signal is transmitted and received according to a transmission / reception mode. The timing diagram 301 is a timing diagram showing the types of signals transmitted from the transmitting end of the RFID transceiver, the timing diagram 302 is a timing diagram indicating whether a signal is received from the tag, and the timing diagram 303 is a signal for the RFID transceiver. Is a timing diagram showing whether the controller is operating in a transmission mode (Tx mode) for transmitting a signal or in a reception mode (Rx mode) for receiving a signal. It is also.

When the transceiver operates in the Rx mode, the transmitting end performs frequency upconversion of the continuous waveform CW to transmit energy to the tag (TxCW), and data is received through the receiving end (RxDATA). When the transceiver operates in the transmission mode (Tx mode), since there is no signal input to the analog-to-digital converter 108, no signal is received, and data is transmitted through the transmitter (TxDATA). As such, the control signal RxTxb is transmitted from the control unit 110 to the first to third switches 103, 105, and 112 to control the transmission mode and the reception mode of the transceiver. In one embodiment, when the transceiver operates in the Rx mode, the control signal RxTxb is transmitted with a “high” value, such that the second switch 105 transmits the continuous waveform generator 111. The mixer 106 is connected, the first switch 103 connects the receiving mixer 102 and the low band filter 104, and the third switch 112 is the low band filter 104 and the analog-to-digital converter ( 108). In addition, when the transceiver is operating in the transmission mode (Tx mode), the control signal (RxTxb) is transmitted a "low" value, so that the second switch 105 and the third switch 112 is a transmission mixer 106 ) And the low band filter 104, and the first switch 103 connects the digital-to-analog converter 109 and the low band filter 104.

In consideration of the switching speeds of the switches 103, 105, and 112 when the transmission mode and the reception mode are switched, a margin Tm is provided at the time of switching the control signal RxTxb and at the start and end of the transmission mode and the reception mode. You must switch between the transmit and receive modes.

As such, the transmitter / receiver shares the low-band filter 104 at the RF / analog end of the RFID transceiver to reduce the overall circuit area of the transceiver. In addition, since power consumption due to the bias of the low pass filter can be reduced, overall power consumption can be achieved.

Next, an RFID transceiver according to another embodiment of the present invention will be described with reference to FIG. 4. The RFID transceiver according to another embodiment of the present invention includes a low noise buffer 113 between the reception mixer 102 and the first switch 103. The low noise buffer 113 is a component that plays a role of a low noise amplifier in a radio frequency band in a baseband, and amplifies a signal while suppressing noise amplification as much as possible. By including the low noise buffer 113, good reception performance can be achieved even when the signal-to-noise ratio is low.

According to another embodiment of the present invention, as described above, the RFID transceiver includes a programmable gain amplifier 114 at the rear of the low band filter 104 to amplify the signal filtered by the low band filter 104. Can be. Herein, the gain of the programmable gain amplifier 114 may be arbitrarily adjusted according to the magnitude of the received signal, or the gain may be adjusted to a value predetermined by the user. In this case, the programmable gain amplifier 114 may be provided between the third switch 112 and the low band filter 104 or between the third switch 112 and the analog-to-digital converter 108. When a programmable gain amplifier 114 is provided between the third switch 112 and the low band filter 104, it amplifies the baseband signal during transmission and reception, and the third switch 112 and the analog-to-digital converter ( 108 amplifies the baseband signal only upon reception. By providing the programmable gain amplifier 114, the size of the signal input to the analog-to-digital converter can be maintained within a certain range, thereby improving reception performance.

As mentioned above, although this invention was demonstrated by the limited embodiment and drawing, those skilled in the art will clearly understand that this is not intended to limit the scope of the present invention, but is only an illustration. Furthermore, those skilled in the art will be able to realize various modifications or equivalent inventions of the present invention by the detailed description of the invention. Accordingly, the present invention is intended to cover such modifications and equivalent inventions as fall within the scope and spirit of the invention.

1 is a block diagram of an RFID transceiver according to an embodiment of the present invention.

2 is a diagram illustrating a signal transmission path when an RFID transceiver transmits a signal to a tag according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a signal transmission / reception in the transmission / reception mode according to an embodiment of the present invention, and a timing diagram of a control signal of the control unit 110.

4 is a block diagram of an RFID transceiver according to another embodiment of the present invention.

Claims (9)

A filter for selectively receiving and filtering a received baseband signal or a transmitted baseband signal; A transmission mixer for generating a transmission radio frequency signal by frequency upconverting the signal from which the transmission baseband signal is filtered by the filter; And And a control unit controlling an input signal selection of the transmission mixer and the filter. The method of claim 1, A low noise amplifier for amplifying a received radio frequency signal; A receive mixer for generating the received baseband signal by frequency downconverting the signal amplified by the low noise amplifier; And And a drive amplifier for amplifying the transmit radio frequency signal. The method of claim 1, A digital-analog converter for converting a transmit digital signal into the transmit baseband signal; And And an analog-digital converter in which the received baseband signal converts the signal filtered by the filter into a received digital signal. The method of claim 1, Further comprising a first switch for selecting the signal input to the filter, And the first switch is controlled by the control unit. The method of claim 1, The transmission mixer selectively receives the transmission baseband signal filtered by the filter or a predetermined continuous wave signal, The RFID transceiver further includes a second switch for selecting a signal input to the transmission mixer, And the second switch is controlled by the control unit. The method of claim 3, And a third switch for selectively transferring the output signal of the filter to the analog-to-digital converter or the transmission mixer, And the third switch is controlled by the control unit. The method of claim 1, And a low noise buffer in front of the filter for low noise amplifying the received baseband signal. The method of claim 1, And a programmable gain amplifier for amplifying the signal filtered by the filter. The method according to any one of claims 1 to 8, The filter is a lowpass filter or a bandpass filter.

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